(function(win, lib) {
    var doc = win.document;
    var docEl = doc.documentElement;
    var metaEl = doc.querySelector('meta[name="viewport"]');
    var flexibleEl = doc.querySelector('meta[name="flexible"]');
    var dpr = 0;
    var scale = 0;
    var tid;
    var flexible = lib.flexible || (lib.flexible = {});
    if (metaEl) {
        console.warn("将根据已有的meta标签来设置缩放比例");
        var match = metaEl.getAttribute("content").match(/initial\-scale=([\d\.]+)/);
        if (match) {
            scale = parseFloat(match[1]);
            dpr = parseInt(1 / scale)
        }
    } else {
        if (flexibleEl) {
            var content = flexibleEl.getAttribute("content");
            if (content) {
                var initialDpr = content.match(/initial\-dpr=([\d\.]+)/);
                var maximumDpr = content.match(/maximum\-dpr=([\d\.]+)/);
                if (initialDpr) {
                    dpr = parseFloat(initialDpr[1]);
                    scale = parseFloat((1 / dpr).toFixed(2))
                }
                if (maximumDpr) {
                    dpr = parseFloat(maximumDpr[1]);
                    scale = parseFloat((1 / dpr).toFixed(2))
                }
            }
        }
    }
    if (!dpr && !scale) {
        var isAndroid = win.navigator.appVersion.match(/android/gi);
        var isIPhone = win.navigator.appVersion.match(/iphone/gi);
        var devicePixelRatio = win.devicePixelRatio;
        if (isIPhone) {
            if (devicePixelRatio >= 3 && (!dpr || dpr >= 3)) {
                dpr = 3
            } else {
                if (devicePixelRatio >= 2 && (!dpr || dpr >= 2)) {
                    dpr = 2
                } else {
                    dpr = 1
                }
            }
        } else {
            dpr = 1
        }
        scale = 1
    }
    docEl.setAttribute("data-dpr", dpr);
    if (!metaEl) {
        metaEl = doc.createElement("meta");
        metaEl.setAttribute("name", "viewport");
        metaEl.setAttribute("content", "initial-scale=" + scale + ", maximum-scale=" + scale + ", minimum-scale=" + scale + ", user-scalable=no");
        if (docEl.firstElementChild) {
            docEl.firstElementChild.appendChild(metaEl)
        } else {
            var wrap = doc.createElement("div");
            wrap.appendChild(metaEl);
            doc.write(wrap.innerHTML)
        }
    }

    function isPC() {
        var userAgentInfo = navigator.userAgent;
        var Agents = new Array("Android", "iPhone", "SymbianOS", "Windows Phone", "iPad", "iPod");
        var flag = true;
        for (var v = 0; v < Agents.length; v++) {
            if (userAgentInfo.indexOf(Agents[v]) > 0) {
                flag = false;
                break;
            }
        }
        return flag;
    }

    function refreshRem() {
        var width = docEl.getBoundingClientRect().width;
        if (width / dpr > 750) {
            width = 750 * dpr
        }
        var rem = width / 3.75;
        if (isPC()) {
            docEl.style.fontSize = "100px";
        } else {
            docEl.style.fontSize = rem + "px";
        }
        flexible.rem = win.rem = rem
    }
    win.addEventListener("resize", function() {
        clearTimeout(tid);
        tid = setTimeout(refreshRem, 300)
    }, false);
    win.addEventListener("pageshow", function(e) {
        if (e.persisted) {
            clearTimeout(tid);
            tid = setTimeout(refreshRem, 300)
        }
    }, false);
    if (doc.readyState === "complete") {
        doc.body.style.fontSize = 12 * dpr + "px"
    } else {
        doc.addEventListener("DOMContentLoaded", function(e) {
            doc.body.style.fontSize = 12 * dpr + "px"
        }, false)
    }
    refreshRem();
    flexible.dpr = win.dpr = dpr;
    flexible.refreshRem = refreshRem;
    flexible.rem2px = function(d) {
        var val = parseFloat(d) * this.rem;
        if (typeof d === "string" && d.match(/rem$/)) {
            val += "px"
        }
        return val
    };
    flexible.px2rem = function(d) {
        var val = parseFloat(d) / this.rem;
        if (typeof d === "string" && d.match(/px$/)) {
            val += "rem"
        }
        return val
    }
})(window, window["lib"] || (window["lib"] = {}));